Structural Organisation Of The Brainstem Flashcards
What is the brainstem made up of?
Medulla oblongata
Pons
Midbrain
If the brainstem were to be cut in transverse sections what would the four areas seen be?
(Posterior to anterior)
Tectum (roof of ventricular system)
Ventricular system
Tegmentum (core of the brainstem)
Basal portion (most anterior)
What are the three broad functions of the brainstem?
Connects the tracts to higher centres
Contains reflex centres
Houses nuclei of cranial nerves 3-12
Where is the midbrain/ mesencephalon found?
Located between the Diencephalon and the pons
Where is the cerebral aqueduct found?
The cerebral aqueduct is hollow and runs through the midbrain and connects the 3rd and 4th ventricles
Which cranial nerves emerge from the midbrain?
Oculomotor (3)
Trochlear (4)
What is the corpora quadrigemina?
It is a reflex centre that connects the midbrain to the hindbrain
How is the corpora quadrigemina divided?
2 superior colliculi
2 inferior colliculi
What reflexes are the superior colliculi responsible for?
Control reflex movements of the eyes, neck, and head in response to visual stimuli
What reflexes are the inferior colliculi responsible for?
Control reflex movements of the head, neck and trunk in response to auditory stimuli
Where is the red nucleus found?
It is a large subcortical structure in the ventral midbrain
How is the red nucleus divided?
The red nucleus is cytoarchitectonically divided into two histologically distinct subregions
What are the two regions of the red nucleus?
A magnocellular caudal region - large sparse neurones
Rostral parvocellular region - small and medium neurones
What’s the role of the red nucleus?
It is a relay station
And integrates information
Issues subconscious motor commands concerned with muscle tone and posture
Where does the red nucleus receive information from?
It contains various blood vessels and will receive information from the cerebrum and cerebellum
Where is the substantia nigra?
It is found lateral to the red nucleus
What does the substantia nigra do?
The melanin containing substantia nigra secretes dopamine to inhibit the excitatory neurones of the basal nuclei
What is the difference between a healthy individuals and someone with Parkinson’s brain scan?
The Parkinson’s patient will lack dark spots (Dopaminergic neurones) as there is damage to the substantia nigra
Where is the pons found?
The pons is found between the midbrain and medulla oblongata
Acts as a bridge?
What are the two surfaces of the pons?
Anterior surface - large bulge (basilar pons)
Posterior surface - cerebellar peduncles (tegmentum)
Where is the locus coeruleus found?
It is located within the dorsal wall of the upper pons, under the cerebellum in the caudal midbrain
It is also surrounded by the 4th ventricle
What is the importance of the locus coeruleus?
This nucleus is one of the main sources of noradrenaline in the brain
It is composed of mostly medium sized neurones